sometimes you need a filter. You can use content mangement system to block s-e-x pages that come up randomly in internet searches. In firefox i use adblock which is useful in blocking annoying p-o-r-n.
With 4 children I feel compelled to use a filter. We use BSafe filter. I have spoken several times on the importance of using the internet safely! Several filters can be seen here: http://cyber.colossians2.com/index_files/page0003.html